July 19, 2012

Background Radiation Levels

The U.K. Health Protection Agency estimates the typical Briton receives about 2,200 microsieverts of radiation per year from background radiation, or about 0.251 microsieverts per hour -- more than double the levels registered in Tokyo. Rome is also about 0.25 microsieverts per hour.

“Half of the average annual radiation to people in the U.K. comes from radon -- an invisible, colorless, radioactive gas present in all soils,” John Harrison, deputy director of the agency’s radiation center. Cornwall, a popular tourist destination in southwest England, has four times the level of radon as other parts of the country.

The highest level of background radiation is in the state of Kerala and city of Chennai in southern India, where people receive average doses above 30 millisieverts per year, or 3.42 microsieverts an hour, according to the World Nuclear Association. India has vast amounts of thorium in its soil. A millisievert is 1,000 microsieverts.

In Brazil and Sudan, exposure can reach 40 millisieverts a year or 4.57 microsieverts an hour.


Background radiation is 50 times higher than New York in the Sudan and parts of India.
Background radiation is 5 times higher than New York in India in general
Background radiation is almost 3 times higher than New York in the UK

Radiation levels are also far higher on planes.
Long term studies do not show increased deaths from the radiation

Here is a Japanese paper about radiation around the world


Here is a site that discusses radiation risks and levels from various common sources.



How can parents in Brazil, Sudan, India be so irresponsible as to let their children grow up with so much radiation ?

An MIT study of mice at 400 times normal background levels showed no excess DNA damage.

A study of people in Kerala showed no increase in radiation deaths

The coastal belt of Karunagappally, Kerala, India, is known for high background radiation (HBR) from thorium-containing monazite sand. In coastal panchayats, median outdoor radiation levels are more than 4 mGy y-1 and, in certain locations on the coast, it is as high as 70 mGy y-1. Although HBR has been repeatedly shown to increase the frequency of chromosome aberrations in the circulating lymphocytes of exposed persons, its carcinogenic effect is still unproven. A cohort of all 385,103 residents in Karunagappally was established in the 1990's to evaluate health effects of HBR. Based on radiation level measurements, a radiation subcohort consisting of 173,067 residents was chosen. Cancer incidence in this subcohort aged 30-84 y (N = 69,958) was analyzed. Cumulative radiation dose for each individual was estimated based on outdoor and indoor dosimetry of each household, taking into account sex- and age-specific house occupancy factors. Following 69,958 residents for 10.5 years on average, 736,586 person-years of observation were accumulated and 1,379 cancer cases including 30 cases of leukemia were identified by the end of 2005. Poisson regression analysis of cohort data, stratified by sex, attained age, follow-up interval, socio-demographic factors and bidi smoking, showed no excess cancer risk from exposure to terrestrial gamma radiation. The excess relative risk of cancer excluding leukemia was estimated to be -0.13 Gy-1 (95% CI: -0.58, 0.46). In site-specific analysis, no cancer site was significantly related to cumulative radiation dose. Leukemia was not significantly related to HBR, either. Although the statistical power of the study might not be adequate due to the low dose, our cancer incidence study, together with previously reported cancer mortality studies in the HBR area of Yangjiang, China, suggests it is unlikely that estimates of risk at low doses are substantially greater than currently believed.

No extra deaths for air crews who can get flying long haul routes for ten years would get 30-90 milliSv (30,000 to 90,000 microsieverts) and for 20 year would get 60-180 milliSv

I had a previous article about radiation compared to other risks of smoking, being overweight, and regular occupational risks


Health Risk Est. life expectancy lost

Smoking 20 cigs a day                   6 years
Overweight (15%)                        2 years
Alcohol (US Ave)                        1 year
All Accidents                           207 days
All Natural Hazards                     7 days
Occupational dose (300 mrem/yr)         15 days
Occupational dose (1 rem/yr)            51 days
You can also use the same approach to looking at risks on the job:

Industry type Est. life expectancy lost

All Industries                          60 days
Agriculture                             320 days
Construction                            227 days
Mining and quarrying                    167 days
Manufacturing                           40 days
Occupational dose (300 mrem/yr)         15 days
Occupational dose (1 rem/yr)            51 days


Sievert metric radiation unit at wikipedia

* 1 Sv (Sievert) = 100 rem
    * 1 mSv = 100 mrem = 0.1 rem
    * 1 μSv = 0.1 mrem
    * 1 rem = 0.01 Sv = 10 mSv
    * 1 mrem = 0.00001 Sv = 0.01 mSv = 10 μSv

Counts per minute at wikipedia

* One becquerel (Bq) is equal to one disintegration per second, or 60 dpm.
* One curie (Ci) is equal to 3.7 x 10 10 Bq or dps, which is equal to 2.22 x 10^12 dpm.

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